YOU can have all the opinion polls in the world but none of them casts a single vote.

That's one reason why the results of Thursday's local elections are so important.

Most obviously, they matter because they determine the make-up of local authorities. But with the General Election less than five weeks away they also matter because they show that the message of the opinion polls is bang-on: we are on course for a Conservative landslide.

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On one level that's a simple product of Labour's collapse under Jeremy Corbyn. He is toxic and voters are running a mile.

Traditionally, council elections lead to a protest vote against the sitting government. Thursday's were, uniquely, a protest vote against the opposition.

But there's another reason why Theresa May will be returned to Downing Street with a thumping majority: the collapse of the Ukip vote and the more or less straight switch of Ukip votes to the Conservatives.

In 2013 Ukip averaged a quarter of the votes in every ward it contested. That gave it 147 councillors. On Thursday, it lost almost every seat it contested. It's that combination of factors which is so fantastic for the Tories - and such a nightmare for Labour.

It became unstoppable as a political force

There's no denying that Thursday was an utter disaster for Ukip - and the General Election will almost certainly be the same.

But disaster as it was, Ukip can nonetheless claim to have been the most successful party in British history. It had one aim and it achieved it. And in doing so it has changed Britain for ever.

Nigel Farage in pictures

Mon, April 3, 2017

Nigel Farage is a British politician who has been the leader of the UK Independence Party since October 2016.

Ukip is a victim of its astonishing success. When it was founded in 1993 (by renaming the Anti-Federalist League, set up two years earlier), the cause of Britain's withdrawal from the EU was regarded by the political establishment not so much as a fringe idea as the preserve of madmen.

And yet just 23 years later - barely a blink of the eye in the stretch of our history - Britain voted to leave.

It is the understatement of the century to describe that as a success for Ukip. In truth, for the first 13 years of its existence Ukip was indeed a fringe party.

It started to make a real impact only when Nigel Farage became leader in 2006.

Farage's skill was his ability to tap into British voters' longstanding Euroscepticism using language and ideas that resonated across the spectrum.

So brilliantly was he able to do this that Ukip actually won the 2014 European elections - the first time that a party other than the Conservatives or Labour had won a national election for more than a century.

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Thursday's local elections were a protest vote against the opposition

Both main parties had their Eurosceptics but it was only when Ukip started to convert Europe into hard votes for pulling out that the issue became unstoppable as a political force.

Alongside this, the decision in November 2010 of this newspaper to advocate withdrawal also brought the cause from the fringes to the mainstream. Advocates of withdrawal all say that when the Daily Express started to support withdrawal, they realised for the first time that it really could happen.

Such was the political pressure that David Cameron had no realistic choice but to concede a referendum. First, his own party would not have allowed him to carry on without one. But more importantly it was clear that the public demand was overwhelming.

Pro-Europeans in both parties had spent years contemptuously ignoring all opposition to further European integration. But the rise of Ukip and the threat it posed to both main parties meant that the demand for a referendum on Brexit was like a pressure cooker on the point of exploding.

The rest is history: on June 23 last year we voted to leave the EU. For a party named the United Kingdom Independence Party, derided as a joke for so long, it was a complete and total triumph.

But it did not take a genius political forecaster to predict that its moment of triumph also spelt its death.

Nigel Farage and his successors as leader (the endless infighting didn't do the party any good) all attempted to position Ukip as more than a one-trick pony, with policies across the whole spectrum of political issues designed to capitalise on the feeling that the mainstream parties were not speaking for many voters.

That was the right tactic. But realistically Ukip was always a single-issue party. In voters' minds the name was the giveaway.

And just to ram that home, under Theresa May the Conservatives have made concerted efforts to reclaim the mantle they held under Baroness Thatcher of a party that speaks for hard-working Brits.

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Theresa May will return to Downing Street with the switch of Ukip votes to the Conservatives

The Conservatives have stolen Ukip's thunder.

And with no serious opposition from Labour it's important to recognise that Ukip's support did not come solely from disenchanted Tories. It also had considerable support from disaffected Labour voters.

And the message of Thursday's vote is that these former Labour voters are not going back. They are either not voting or switching straight to the Tories.

This will destroy Labour next month. It would lose at least 61 of its 100 marginal seats if Ukip voters switch to the Tories - and even more if, as seems certain, some Labour voters join them.

So Ukip may be dying but its impact has been profound: it has helped bring us out of the EU - and now its legacy is destroying Labour. Not bad for a so-called fringe party.